Am Donnerstag, den 02.06.2005, 12:46 -0700 schrieb Ben: > You mean, you want to be able to say something like: > > select isConnected(a,b) > > and get back a true/false, or maybe the path? > > That seems quite doable in SQL, assuming you either store those results > and simply use sql to retrieve them, or use a stored proc to compute the > result each time. These are both things I want to avoid. I am not trying to solve a real world problem, I want to understand the limits of SQL. And it seems that a plain SELECT that tells me if a path exists is not possible. However I just read nested sets (thx for the link, Sean). Maybe a tricky representation does it. Sincerely, Joachim ---------------------------(end of broadcast)--------------------------- TIP 5: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq